Eruptions of the Yellowstone volcanic system have included the two largest volcanic eruptions in North America in the past few million years; the third largest was at Long Valley in California and produced the Bishop ash bed.
On the diesel Passat, the TDI badge stands for Turbocharged Direct Injection, which isn't really all that helpful as the gasoline-powered Passat is also turbocharged and also uses direct injection. Volkswagen attempts to clear this up by calling this Passat the Passat TDI Clean Diesel.
TSI is our pioneering technology for petrol engines. TSI engines are compact, high-powered and use less fuel. TSI technology blends the best of our TDI diesel and FSI (Fuel Stratified Injection) engines. You enjoy excellent driveability and outstanding fuel economy. Acceleration is instant, whichever gear you're in.